Process for production of an oxetane

ABSTRACT

A process for production of an oxetane, which process comprises subjecting an alcohol having two or more hydroxyl groups to reaction with a carbamide at a molar ratio employing 1-2 moles of said carbamide on 1-2 moles of said alcohol. The alcohols preferably have at least one 1,3-diol grouping. The reaction is carried out in the presence of at least one catalyst promoting and/or initiating transcarbonylation and/or pyrolysis. A reaction mixture comprising an oxetane and optionally an orthocarbonate of said alcohol is yielded. The oxetane is suitable recovered from said reaction mixture by for instance distillation.

This application is a 371 of PCT/SE99/02267 dated Dec. 6, 1999.

The present invention refers to a novel, simple and inexpensive processfor manufacture of an oxetane, which process provides technical as wellas environmental advantages. The process includes subjecting an alcohol,having at least two hydroxyl groups, to a reaction with a carbamidecompound in the presence of at least one catalyst.

Oxetanes as disclosed and produced by the process of the presentinvention are compounds having at least one four-membered ring ofgeneral formula (I)

Oxetanes have been prepared by a number of synthetic methods. Thegenerally available methods include

ring closure of 1,3-diol derivatives by the intramolecular Williamsonreaction,

decomposition of cyclic carbonate esters, and

photochemical reaction of aldehydes and ketones with olefines.

The intramolecular Williamson reaction consists in general of thereaction of 1,3-halohydrins or their acetates with alkali. In 1878trimethylene oxide, oxetane, was prepared for the first time by treating3-chloropropanol with potassium hydroxide. 1,3-halohydrins and acetatesthereof have since been widely used in the preparation of oxetanes. Theuse of acetate esters of said halohydrins often improves the oxetaneyield. Hydrogen sulphate esters and sulphate esters are reported asreplacements for 1,3-halohydrins in the intramolecular Williamsonreaction. Mono(arenesulphonate) esters of 1,3-diols have also been used,especially for preparation of bicyclic oxetanes. Spiro-oxetanes havebeen prepared by treating di(phenylsulphates) with alkali.

Cyclic carbonate esters of diols decompose to oxetanes and carbondioxide. The decomposition is normally carried at 160-260° C. in thepresence of a basic catalyst.

Photochemical reaction of aldehydes and ketones with olefines (the socalled Paterno-Büichi reaction) comprises generally that an olefine andan aldehyde or ketone are irradiated in an inert atmosphere by ahigh-pressure mercury lamp.

Further methods for preparation of oxetanes are disclosed in the patentliterature, including

British patent no. 787,406 disclosing a process for preparing oxetanes,which process comprises reacting a triol with a carbonic acid derivativeof formula O═C(X)₂ wherein X is a halogen atom or an alkyloxy,cycloalkyloxy, aryloxy or tetrahydrofurfuryloxy radical. Compoundsincluded in said formula are for instance phosgene, monoesters ofchlorocarbonic acid and diesters of carbonic acid. The conversionproceeds in two stages and the reaction in respective step is dependenton employed carbonic acid derivative. The use of toxic and highlyhazardous compounds such as phosgene renders the process a large numberof disadvantages and drawbacks.

Japanese Unexamined Patent Publication HEI 10-7669 teaches a method formanufacturing an oxetane having a hydroxymethyl group. The methodcomprises causing a triol to react with an alkyl or alkylene carbonateyielding a cyclocarbonate compound which subsequently is decarboxylatedin the presence of an alkaline catalyst The applicability of disclosedprocess is substantially limited by the fact that employed carbonatesare too expensive for normal industrial use.

Oxetanes can, furthermore, be derived from other oxetanes by forinstance electrolysis, oxidation over a silver catalyst, cyclisation bythe Freund reaction or by substitution of halogen atoms.

Commonly used methods for preparation of oxetanes, the properties ofprepared oxetanes as well as their polymerisation are thoroughlydiscussed in handbooks and encyclopaedias such as “Encyclopedia ofPolymer Science and Technology”, chapter “Oxetane Polymers”, vol 9,1968, pp 668-701, John Wiley & Sons Inc.

The present invention provides unexpectedly a novel, simple, inexpensiveand reliable process for production of an oxetane, which processprovides technical as well as environmental advantages. The process canbe summarised by below simplified reaction scheme (I)

wherein R¹ is —NH₂ or —NR′R″, wherein R′ and R″ is for instance hydrogenor alkyl, and wherein R² and R³ may be a group such as alkyl, aryl orhydroxyalkyl. The process comprises subjecting an alcohol having two ormore hydroxyl groups, which alcohol most preferably has at least one1,3diol grouping, to a reaction with a carbamide at a molar ratioemploying 1-2 moles of said carbamide on 1-2 moles of said alcohol, inthe presence of at least one catalyst promoting and/or initiatingtranscarbonylation and/or pyrolysis. Preferred embodiments of theprocess of the present invention employ 1-1.2 mole of said carbamide on1-1.8 mole of said alcohol. The reaction yields a reaction mixturecomprising said oxetane, which subsequently is recovered by means of forinstance distillation and/or extraction. The reaction is suitablyperformed in an inert atmosphere, such as nitrogen and/or argonatmosphere, and/or at a pressure of 0.01-1 bar, such as 0.1-0.5 bar. Thereaction temperature is in preferred embodiments 100-250° C., such as110-150° C. and/or 170-240° C. A suitable amount of catalyst is normallyfound within the range of 0.01-10 mole%, such as 0.5-2 mole%, calculatedon moles of said alcohol, said carbamide and said catalyst. The reactioncan also optionally be carried out in the presence of one or moresolvents, such as an ethylene glycol, a propylene glycol, a butyleneglycol, a hexanol, a heptanol, an octanol and/or a dodecanol. Suitableamount of said solvent is for instance 0.05-2, such as 0.1-1 or 0.2-0.5,moles on 1 mole of carbamide and alcohol.

A typical procedure can be exemplified as follows:

Carbamide and alcohol are mixed in for instance a molar ratio of 2:1 to1:2, such as a 1:1 to 1:1.8, and at least one catalyst is added in therange of 0.01 to 10 mole %, such as 0.5 to 2 mole %, based on totalmoles of reactants and catalyst. Optionally, combinations of two or morecatalysts can be used. The pressure in the reaction vessel is reduced to0.01-1 bar, such as 0.1-0.5 bar. Optionally, a stream of an inert gas,such as nitrogen or argon, is passed through the vessel. The inert gasmay be used combined with or instead of the reduced pressure. Thetemperature is then raised to 110-150° C., whereby a transcarbonylationstarts. The temperature is preferably kept at 120-140° C. for 1 to 12hours, such as 2 to 5 hours, or until the transcarbonylation iscompleted. A pyrolysis occurs subsequent to said transcarbonylation. Thepressure is preferably reduced to 0.05 to 0.15 bar, such as 0.07 to 0.1bar, and the temperature is slowly raised to 170 to 240° C., such as 180and 200° C. The oxetane formed is suitably for instance continuouslydistilled off from yielded reaction mixture.

The preferred carbamide employed in the process of the present inventionis as disclosed previously a compound of general formula (II)

wherein both substituents R¹ are —NH₂ or wherein each substituent R¹independently is —NR′R″, wherein R′ is hydrogen, linear or branchedalkyl having for instance 1-12, such as 1-8, carbon atoms or is part ofa bond between the nitrogen atoms in the two substituents R′ thus beingpart of a ring formation, and wherein R″ is hydrogen or linear orbranched alkyl having for instance 1-12, such as 1-8, carbon atoms.Carbamide is thus understood as for instance urea, N-alkylurea andN,N-dialkylurea. The preferred carbamide is urea, whereby the twosubstituents R¹ are —NH₂.

The alcohol reacted with said carbamide according to the process of thepresent invention is in preferred embodiments a compound of generalformula (III)

wherein each R² and R³ independently is alky, alkyloxy, alkyloxyalkyl,aryloxyalkyl, hydroxyalkyl, hydroxyalkyloxy, aryl or hydroxyaryl andwherein each R⁴ independently is hydrogen or alkyl. Said alkyl ispreferably linear or branched alkanyl or alkenyl having 1 to 24 such as3-24, 1-12, 4-12 or 2-8, carbon atoms.

The alcohol is in the most preferred embodiments of the presentinvention selected from the group consisting of2,2-dialkyl-1,3-propanediols, 2-alkyl-2-hydroxyalkyl-1,3-propanediolsand 2,2-di(hydroxyalkyl)-1,3-propanediols and/or from the groupconsisting of dimers, trimers and polymers of said 1,3-propanediols.These alcohols can suitably be exemplified by neopentyl glycol,2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol,trimethylolethane monoallyl ether, trimethylolpropane monoallyl ether,pentaerythritol diallyl ether, pentaerythritol monoallyl ether,trimethylolethane, trimethylolpropane, ditrimethylolethane,ditrimethylolpropane, pentaerythritol, dipentacrythritol,tripentaerythritol and esters of dimethylolpropionic acid. Furtherpreferred embodiments include selectively alkoxylated 1,3-propanediolssuch as 2-alkyl-2-hydroxyalkoxy-1,3-propanediols,2,2-di(hydroxyalkyloxy)--1,3-propanediols, wherein alkyloxy is linear orbranched having for instance 3-24, such as 4-12 carbon atoms, orselectively alkoxylated dimers, trimers or polymers thereof Saidselectively alkoxylated 1,3-propanediols can be exemplified byselectively ethoxylated and/or propoxylated trimethylolethane,trimethylolpropane, pentaerythritol, ditrimethylolethane,ditrimethylolpropane, dipentaerythritol or tripentaerythritol. Aselectively alkoxylated 1,3-propanediol or dimer, trimer or polymerthereof as disclosed above is understood as a derivative wherein thehydroxyl groups of the 1,3-diol grouping are non-alkoxylated.

Alkoxylated alcohols can be obtained by reacting at least one alcoholwith at least one alkylene oxide, such as ethylene oxide, propyleneoxide and/or butylene oxide. A suitable alkoxylation degree is forinstance 0.5-10, that is 0.5-10 moles of said alkylene oxide on 1 moleof said alcohol. Selectively alkoxylated alcohols are for instanceobtained from triols, tetrols and higher alcohols having for instance a1,3-diol grouping of formula (III) wherein R² and/or R³ are for instancehydroxyalkyl. The hydroxyl groups of the 1,3-diol grouping of saidformula (I) are before alkoxylation protected and subsequent saidalkoxylation deprotected. A suitable protection method is for instanceacetal formation. Further suitable protection and deprotection methodsare disclosed in for instance “Protective Groups in Organic Synthesis”chapter 2 “Protection for the Hydroxyl Group, Including 1,2- and1,3-diols” by Theodora W. Greene and Peter G. M. Wuts, John Wiley & Sons1991.

The catalyst used in preferred embodiments of the present invention cansuitably be exemplified by KOH, K₂CO₃, NaOH, Na₂CO₃, LiOH, Li₂CO₃, KH,NaH, LiH, KNH₂, NaNH₂, LiNH₂, MgCO₃, Sr(OH)₂, Zn(OH)₂, Zn(OR)₂ whereinOR is alkoxide having 1 to 4 carbon atoms, elemental Na, elemental Li,2-N(R)₂-pyridine or 4N(R)₂-pyridine wherein R is hydrogen or C₁-C₁₈alkyl, trialkylamines, triarylphospine, ZnO, Zn(II)acetate, Zn(O₂CR)₂wherein R is C₂-C₁₇ hydrocarbyl, Zn(X)₂ wherein X is F, Cl, Dr or I,Bu₂SnO or Bu₂Sn(OR)₂ wherein Bu is butyl and OR is alkoxide having 1 to4 carbon atoms, Ti(OR)₄ or Zr(OR)₄ wherein OR is alkoxide having 1 to 4carbon atoms, Ti(X)₄ or Zr(X)₄ wherein X is F, Cl, Br or I, AlH(R)₂wherein R is C₁-C₁₂, AlCl₃, FeCl₃ or Fe(III)acetylacetonate or is acombination of two or more of said compounds.

The oxetane yielded and recovered from the process of the presentinvention is in the most preferred embodiments a compound of generalformula (IV)

wherein each R⁷ and R⁸ independently is alkyl, alkyloxy, alkyloxyalkyl,aryloxyalkyl, hydroxyalkyl, hydroxyalkyloxy, aryl or hydroxyaryl andwherein each R⁹ independently is hydrogen or alkyl. Said alkylpreferably is linear or branched alkanyl or alkenyl having 1-24, such as3-24, 1-12, 4-12 or 2-8, carbon atoms. Substituents R⁷ and R⁸ canoptionally and where applicable suitably comprise one or more oxetanerings of formula (I). The oxetane is in especially preferred embodimentsan oxetane of trimethylolethane, trimethylolpropane, pentaerythritol,ditrimethylolethane, ditrimethylolpropane or dipentaerythritol or is anoxetane of a selectively alkoxylated, such as said ethoxylated and/orpropoxylated, trimethylolethane, trimethylolpropane, pentaerythritol,ditrimethylolethane, ditrimethylolpropane or dipentaerythritol.Selectively alkoxylated is interpreted and suitably exemplified asdisclosed previously, whereby said oxetane in these embodimentspreferably is an oxetane of a 2-alkyl-2-hydroxyalkyloxy-1,3-propanediol,a 2,2-di(hydroxyalkyloxy)-1,3-propanediol or a dimer, trimer or polymerof said 1,3-propanediol Said alkyloxy is as previously disclosedpreferably linear or branched having 3-24, such as 4-12, carbon atoms.

The reaction mixture yielded from the reaction, included in the processof the present invention, between carbamide and alcohol may in additionto said oxetane comprise an orthocarbonate of said alcohol as reactionby-product. Conditions and molar ratio in the process of the presentinvention may be varied to obtain an orthocarbonate of general formula(V)

wherein each R⁵ independently is alkyl, alkyloxy, alkyloxyalkyl,aryloxyalkyl, hydroxyalkyl, hydroxyalkyloxy, aryl or hydroxyaryl andwherein each R⁶ independently is hydrogen or alkyl. Said alkyl ispreferably linear or branched alkanyl or alkenyl having 1-24, such as3-24, 1-12, 4-12 or 2 to 8, carbon atoms. The orthocarbonate may berecovered by methods such as recrystallisation, distillation,extraction, chromatography and the like, and optionally decomposed, suchas hydrolysed under acidic conditions, whereby at least said alcohol isyielded, recovered and preferably recirculated for reaction withcarbamide in accordance with the process of the present invention. Incases where conditions are chosen to allow formation of considerableamounts of the orthocarbonate this may either be separated from yieldedreaction mixture and recovered as a separate product, or may asdisclosed above be hydrolysed to original alcohol and used to repeat theprocess after addition of a proper amount of carbamide.

These and other objects and the attendant advantages will be more fullyunderstood from the following detailed description, taken in conjunctionwith embodiment Examples 1-9.

Examples 1-6, 11 and 12 refer to syntheses in accordance withembodiments of the present invention, yielding an oxetane and inExamples 1-4, 11 and 12 a spiro-orthocarbonate as by-product.

Example 7 refer to NMR characterisation of the oxetane obtained inExamples 1-6.

Example 8 refer to NMR characterisation of the by-product obtained inExamples 1-4.

Example 9 refer to hydrolytic decomposition of the spiro-orthocarbonateobtained in Example 3.

Example 10 refer to synthesis of an oxetane using the alcohol obtainedfrom the decomposition of the spiro-orthocarbonate of Example 9.

EXAMPLE 1

170 moles of urea and 171 moles of a commercially availabletrimethylolpropane (TMP, Perstorp Polyols) were together with 1.5 mole %of zinc(II)acetate and 2 mole % of potassium hydroxide (both based ontotal amount of reactants and catalysts) charged in a reaction vessel.The pressure was reduced to 0.4 bar and the mixture heated to 140° C.for transcarbonylation. The temperature was maintained under stirringfor 5 hours. The pressure was, following the transcarbonylation,decreased to 0.05-01 bar and the temperature was under vigorous stirringslowly raised to 195° C. yielding in a pyrolysis 92.1 moles of3-ethyl-3-hydroxymethyloxetane (trimethylolpropane oxetane). The oxetanewas distilled off as it formed and collected for NMR characterisation(see Example 7). 23.9 moles of spiro-orthocarbonate was yielded asby-product. The spiro-orthocarbonate was also collected and NMRcharacterised (see Example 8).

EXAMPLE 2

418 moles of urea and 507 moles of trimethylolpropane (TMP, PerstorpPolyols) were together with 1.5 mole % of zinc(II)acetate and 2 mole %of potassium hydroxide (both based on total amount of reactants andcatalysts) charged in a reaction vessel. The pressure was reduced to 0.4bar and the mixture heated to 140° C. for transcarbonylation. Thetemperature was maintained under stirring for 5 hours. The pressure was,following the transcarbonylation, decreased to 0.05-01 bar and thetemperature was under vigorous stirring slowly raised to 195° C.yielding in a pyrolysis 213 moles of 3-ethyl-3-hydroxymethyloxetane(trimethylolpropane oxetane). The oxetane was distilled off as it formedand collected for NMR characterisation (see Example 7). 49.9 moles ofspiro-orthocarbonate was yielded as by-product. The spiro-orthocarbonatewas also collected and NMR characterised (see Example 8).

EXAMPLE 3

416 moles of urea and 346 moles of trimethylolpropane (1.%P, PerstorpPolyols) were together with 1.5 mole % of zinc(II)acetate and 2 mole %of potassium hydroxide (both based on total amount of reactants andcatalysts) charged in a reaction vessel. The pressure was reduced to 0.4bar and the mixture heated to 140° C. for transcarbonylation. Thetemperature was maintained under stirring for 5 hours. The pressure was,following the transcarbonylation, decreased to 0.05-01 bar and thetemperature was under vigorous stirring slowly raised to 195° C.yielding in a pyrolysis 173 moles of 3-ethyl-3-hydroxymethyloxetane(trimethylolpropane oxetane). The oxetane was distilled off as it formedand collected for NMR characterisation (see Example 7). 86.5 moles ofspiro-orthocarbonate was yielded as by-product. The spiro-orthocarbonatewas collected, NMR characterised (see Example 8) and hydrolyticallydecomposed (see Example 9).

EXAMPLE 4

416 moles of urea and 346 moles of trimethylolpropane (TMP, PerstorpPolyols) were together with 1.5 mole % of zinc(II)acetate and 2 mole %of potassium hydroxide (both based on total amount of reactants andcatalysts) charged in a reaction vessel. The pressure was reduced to 0.4bar and the mixture heated to 140° C. for transcarbonylation. Thetemperature was maintained under stirring for 1.5 hours. The pressurewas, following the transcarbonylation, decreased to 0.05-01 bar and thetemperature was under vigorous stirring slowly raised to 195° C.yielding in a pyrolysis 168 moles of 3-ethyl-3-hydroxymethyloxetane(trimethylolpropane oxetane). The oxetane was distilled off as it formedand collected for NMR characterisation (see Example 7). The amount ofunreacted trimethylolpropane was determined to 190 moles and the majorconstituent of this remainder was spiro-orthocarbonate. Thespiro-orthocarbonate also was collected and NMR characterised (seeExample 8).

EXAMPLE 5

335 moles of urea and 663 moles of trimethylolpropane (TMP, PerstorpPolyols) were together with 1.5 mole % of zinc(II)acetate and 2 mole %of potassium hydroxide (both based on total amount of reactants andcatalysts) charged in a reaction vessel. The pressure was reduced to 0.4bar and the mixture heated to 140° C. for transcarbonylation. Thetemperature was maintained under stirring for 5 hours. The pressure was,following the transcarbonylation, decreased to 0.05-01 bar and thetemperature was under vigorous stirring slowly raised to 195° C.yielding in a pyrolysis 198 moles of 3-ethyl-3-hydroxymethyloxetane(trimethylolpropane oxetane). The oxetane was distilled off as it formedand collected for NMR characterisation (see Example 7). The amount ofunreacted trimethylolpropane was determined to 465 moles.

EXAMPLE 6

335 moles of urea and 663 moles of trimethylolpropane (TM?, PerstorpPolyols) were together with 1.5 mole % of zinc(II)acetate and 2 mole %of potassium hydroxide (both based on total amount of reactants andcatalysts) charged in a reaction vessel. The pressure was reduced to 0.4bar and the mixture heated to 140° C. for transcarbonylation. Thetemperature was maintained under stirring for 1.5 hours. The pressurewas, following the transcarbonylation, decreased to 0.05-01 bar and thetemperature was under vigorous stirring slowly raised to 195° C.yielding in a pyrolysis 214 moles of 3-ethyl-3-hydroxymethyloxetane(trimethylolpropane oxetane). The oxetane was distilled off as it formedand collected for NMR characterisation (see Example 7). The amount ofunreacted trimethylolpropane was determined to 449 moles.

EXAMPLE 7

The oxetane yielded in Examples 1-6 was NMR characterised to evidencethat 3-ethyl-3-hydroxymethyloxetane (trimethylolpropane oxetane) was theproduct obtained.

Result: ¹H NMR (CDCl₃): δ4.47, 4.41 (4H, CH₂OCH₂, two d); 3.75 (2H,CH₂OH, d), 2.90 (1H, OH, t); 1.73 (2H, q); 0.90 (3H, t) ¹³C NMR(CDCl₃):δ78.46; 65.63; 44.70; 26.58; 8.58

EXAMPLE 8

The spiro-orthocarbonate yielded in Examples 1-4 as by-product was NMRcharacterised, which evidenced the product to be3,9-diethyl-3,9-bis(hydroxymethyl)-1,5,7,11-tetraoxaspiro[5.5] undecane,that is the spiro-orthocarbonate of trimethylolpropane.

Result: ¹H NMR (CDCl₃): δ3.89-3.69 (12 H, m, CH₂O); 1.60 (2H, br, OH);1.36 (4H, q); 0.85(6H, t). ¹³C NMR (CDCl₃): δ115.0 (C_(q)—O); 67.70,67.24 and 61.89 (C—O); 37.02 (C_(q)); 23.44; 7.55. HETCOR analysisconfirmed assignments. MS (CI): 277 (M⁺+1); 161 (M⁺+1-TMPO). HRMS (CI):observed 277.1674, calculated 277.1651 for C₁₃H₂₅O₆. 161.0815,calculated 161.0814 for C₇H₁₃O₄. FTIR (KBr): cm⁻¹ 3569 (s sharp, OH);3500-3100 (s, broad, OH); 1188, 1017 (s, COC).

EXAMPLE 9

24.7 g of the spiro-orthocarbonate obtained in Example 3 andcharacterised in Example 8 was mixed with 150 ml of water and 5 g ofhydrochloric acid (36-w/w HCl). The mixture was heated to 100° C. for 60minutes and subsequently evaporated in vacuum. The remainder after saidevaporation consisted of 24 g of essentially pure trimethylolpropane.

EXAMPLE 10

Example 1 was repeated with the difference that the commerciallyavailable trimethylolpropane was replaced by trimethylolpropane obtainedas in Example 9, whereby ca. 92 moles of 3-ethyl-3-hydroxymethyloxetane(trimethylolpropane oxetane) and ca 24 moles of spiro-orthocarbonate asby-product was yielded.

EXAMPLE 11

402 mmoles of trimethylolethane and 335 mmoles of carbamide weretogether with 1.1 mole % of potassium hydroxide (based on total amountof reactants and catalysts) charged in a reaction vessel. The synthesiswas performed in accordance with Example 1. 60 mmoles of3-hydroxymethyl-3-methyloxetane (trimethylolethane oxetane) was yieldedfrom the distillate and characterised by NMR. The remainder containedthe spiro-orthocarbonate yielded as by-product.

EXAMPLE 12

84.5 mmoles of trimethylolhexane and 70.9 mmoles of carbamide weretogether with 1.2 mole % of potassium hydroxide (based on total amountof reactants and catalysts) charged in a reaction vessel. The synthesiswas performed in accordance with Example 1. The temperature uring thepyrolysis gradually raised to 215° C. 20.6 mmoles of3-hydroxymethyl-3-pentyloxetane (trimethylolhexane oxetane) was yieldedfrom the distillate and characterised by NMR. The remainder containedthe spiro-orthocarbonate (3% on the carbamide) yielded as by-product.

While particular embodiments of the invention have been shown, it willbe understood, of course, that the invention is not limited theretosince many modifications may be made, and it is, therefore, contemplatedto cover by the appended claims any such modifications as fall withinthe true spirit and scope of the invention.

What is claimed is:
 1. A process for production of an oxetane, whichprocess comprises subjecting an alcohol having two or more hydroxylgroups to reaction with a carbamide, at a molar ratio employing 1 to 2moles of said carbamide on 1 to 2 moles of said alcohol and in thepresence of at least one catalyst promoting and/or initiatingtranscarbonylation and/or pyrolysis, whereby a reaction mixturecomprising at least one oxetane, and optionally at least oneorthocarbonate, of said alcohol is yielded, and wherein said oxetane andoptionally said orthocarbonate is recovered from said reaction mixture.2. A process according to claim 1, wherein 1 to 1.2 mole of saidcarbamide is employed on 1 to 1.8 mole of said alcohol.
 3. A processaccording to claim 1, wherein said carbamide is a compound of generalformula (H)

wherein R′ is —NH2 or wherein each R¹ independently is —NR′R″, whereinR′ is part of a bond between respective nitrogen atom in substituentsR¹, hydrogen or alkyl and wherein R′ is hydrogen alkyl.
 4. A processaccording to claim 3, wherein said alkyl is linear or branched alkanylor alkenyl having 1 to 12, such as 1 to 8, carbon atoms.
 5. A processaccording to claim 3, wherein R¹ is —NH₂, whereby said carbamide isurea.
 6. A process according to claim 1, wherein said alcohol has atleast one 1,3-diol grouping.
 7. A process according to claim 1, whereinsaid alcohol is an alcohol of general formula (III)

wherein each R² and R³ independently is alkyl, alkyloxy, alkyloxyalkyl,aryloxyalkyl, hydroxyalkyl or hydroxyalkyloxy, aryl or hydroxyaryl andwherein each R⁴ independently is hydrogen or alkyl.
 8. A processingaccording to claim 1, wherein said alcohol is a2,2-dialkyl-1,3-propanediol, a 2-alkyl-2-hydroxyalkyl-1,3-propanediol, a2,2-di(hydroxyalkyl)-1,3-propanediol or a dimer, trimer or polymer ofsaid 1,3-propanediol.
 9. A process according to claim 7, wherein saidalkyl is linear or branched alkanyl or alkenyl having 1 to 24, such as 3to 24, 1 to 12, 4 to 12 or 2 to 8, carbon atoms.
 10. A process accordingto claim 1, wherein said alcohol is neopentyl glycol,2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol,trimethylolethane monallyl ether, trimethylolpropane monoallyl ether,pentaerythritol diallyl ether, pentaerythritol monoallyl ether,trimethylolethane, trimethylolpropane, ditrimethylolethane,ditrimethylolpropane, pentaerythritol, dipentaerythritol ortripentaerythritol.
 11. A process according to claim 1, wherein saidalcohol is a 2-alkyl-2-hydroxyalkyloxy-1,3-propanediol, a2,2-di(hydroxyalkyloxy)-1,3-propanediol or a dimer, trimer or polymer ofsaid 1,3-propanediol.
 12. A process according to claim 11, wherein saidalkyloxy is linear or branched having 3 to 24, such as 4 to 12, carbonatoms.
 13. A process according to claim 1, wherein said reaction isperformed at a temperature of 100 to 250° C., such as 110 to 150° C.and/or 170 to 240° C.
 14. A process according to claim 13, wherein saidtemperature is applied in two or more steps, whereby a first temperatureof 110 to 150° C., preferably 120 to 140° C., and a final temperature of170 to 240° C., preferably 180 to 200° C., are applied.
 15. A processaccording to claim 1, wherein said reaction is performed at a pressureof 0.01 to 1 bar, such as 0.1 to 0.5 bar.
 16. A process according toclaim 1, wherein said reaction is performed in an inert atmosphere, suchas nitrogen and/or argon atmosphere.
 17. A process according to claim 1,wherein said reaction is performed in the presence of at least onesolvent.
 18. A process according to claim 17, wherein said solvent is anethylene glycol, a propylene glycol, a butylene glycol, pentanol, ahexanol, a heptanol, an octanol and/or a dodecanol.
 19. A processaccording to claim 17, wherein said solvent is added in an amountcorresponding to 0.05 to 2, such as 0.1 to 1 or 0.2 to 0.5, moles on 1mole of said carbamide and said alcohol.
 20. A process according toclaim 1, wherein said catalyst is employed in an amount of 0.01 to 10mole %, preferably 0.5 to 2 mole %, calculated on subtotal moles of saidalcohol, said carbamide and said catalyst.
 21. A process according toclaim 1, wherein said catalyst is KOH, K₂CO₃, NaOH, Na₂CO₃, LiOH,Li₂CO₃, KH, NaH, LiH, KNH₂, NaNH₂, LiNH₂, MgCO₃, Sr(OH)₂, Zn(OH)₂,Zn(OR)₂ wherein OR is alkoxide having 1 to 4 carbon atoms, elemental Na,elemental Li, 2-N(R)₂-pyridine or 4-N(R)₂-pyridine wherein R is hydrogenor C₁-C₁₈ alkyl, trialkylamines, triarylphospine, ZnO, Zn(II)acetate,Zn(O₂CR)₂ wherein R is C₂-C₇ hydrocarbyl, Zn(X)₂ wherein X is F, Cl, Bror I, Bu₂SnO or Bu₂Sn(OR)₂ wherein Bu is butyl and OR is alkoxide having1 to 4 carbon atoms, Ti(X)₄ or Zr(X)₄ wherein X is F, Cl, Br or I,AlH(R)₂ wherein R is C₁-C₁₂, AlCl₃, FeCl₃ or Fe(III)acetylacetonate oris a combination of two or more of said compounds.
 22. A processaccording to claim 1, wherein said oxetane is a compound of generalformula (IV)

wherein each R⁷ and R8 independently is alkyl, alkyloxy, alkyloxyalkyl,aryloxyalkyl, hydroxyalkyl or hydroxyalkyloxy, aryl or hydroxyaryl andwherein each R⁹ independently is hydrogen or alkyl.
 23. A processaccording to claim 22, wherein, said alkyl is linear or branched alkanylor alkenyl having 1 to 24, such as 3 to 24, 1 to 12, 4 to 12 or 2 to 8,carbon atoms.
 24. A process according to claim 1, wherein said oxetaneis an oxetane of trimethylolethane, trimethylolpropane, pentaerythritol,ditrimethylolethane, ditrimethylolpropane or dipentaerythritol.
 25. Aprocess according to claim 1, wherein said oxetane is an oxetane of a2-alkyl-2-hydroxyalkyloxy-1,3-propanediol, a2,2-di(hydroxyalkyloxy)-1,3-propanediol or a dimer, trimer or polymer ofsaid 1,3-propanediol.
 26. A process according to claim 25, wherein saidalkyloxy is linear or branched having 3 to 24, such as 4 to 12, carbonatoms.
 27. A process according to claim 1, wherein said oxetane isrecovered from said reaction mixture by distillation.
 28. A processaccording to claim 1, wherein said reaction mixture yielded from saidreaction between carbamide and alcohol comprises said orthocarbonate ofsaid alcohol.
 29. A process according to claim 28, wherein saidorthocarbonate is recovered and optionally decomposed under acidicconditions, whereby at least said alcohol is yielded, recovered andrecirculated for reaction with said carbamide.
 30. A process accordingto claim 28, wherein said orthocarbonate is a compound of generalformula (V)

wherein each R⁵ independently is alkyl, alkyloxy, alkyloxyalkyl,aryloxyalkyl, hydroxyalkyl or hydroxyalkyloxy, aryl or hydroxyaryl andwherein said R⁶ independently is hydrogen or alkyl.
 31. A processaccording to claim 30, wherein said alkyl is linear or branched alkanylor alkenyl having 1 to 24, such as 3 to 24, 1 to 12, 4 to 12 or 2 to 8,carbon atoms.
 32. A process according to claim 28, wherein saidorthocarbonate is3,9-diethyl-3,9-bix(hydroxymethyl)-1,5,7,11-tertraoxaspiro[5.5]undecane.